Simulation of pulsed dynamic nuclear polarization in the steady state

Area of Science:

• Magnetic Resonance
• Quantum Control

Background:

• Pulsed dynamic nuclear polarization (DNP) enhances bulk nuclear polarization using microwave pulse sequences.
• Current DNP pulse sequence design relies on one-time spin transfer analysis, failing to predict optimal repetition times.
• Real DNP experiments involve a balance between electron polarization transfer and nuclear relaxation.

Purpose of the Study:

• To explore and compare algorithms for computing the stroboscopic steady state in pulsed DNP.
• To identify efficient and stable computational methods for DNP simulations.
• To validate simulation results against experimental data and assess their implications for pulse sequence design.

Main Methods:

• Explicit time evolution via propagator squaring.
• Effective propagator generation using matrix logarithm.
• Direct steady-state calculation with the Newton-Raphson method.

Main Results:

• The Newton-Raphson method and propagator squaring are stable algorithms for DNP steady-state computation.
• The Newton-Raphson method demonstrates superior computational efficiency.
• Simulations show good agreement with experimental DNP results across various magnetic fields (0.34-3.4 T).

Conclusions:

• Efficient algorithms, particularly Newton-Raphson, enable accurate prediction of DNP steady states.
• Accounting for spin system distributions improves simulation accuracy.
• The dynamic trajectory differs from the steady orbit, impacting DNP pulse sequence optimization.